More than ever, railcar owners and operators need a better understanding of how their assets are performing. With heavier cars in service, there is a greater need to identify “bad actors” (cars which can damage track infrastructure and lead to derailments) as soon as their performance becomes unacceptable. There is also a need to increase average train speed by improving high speed performance and reducing unplanned service interruptions through mechanical failures. Car owners increasingly seek to implement preventative maintenance programs to avoid mechanical failures and schedule repairs at a facility and time of their choice. Finally, with more automation of rail operations and increasing regulation to improve safety, the railroad industry needs new ways to monitor the performance of trains, cars and railcar trucks.
Some of the performance criteria that need to be monitored include roller bearing condition and temperature, roller bearing adapter displacement, wheel condition, truck hunting/warp/binding, brake status and performance, whether a partial derailment has occurred and potentially problematic track condition. Since some of these performance problems could lead very quickly to a catastrophic failure of the train, it is desirable to monitor and report exceptions to the locomotive or to a central data handling facility as quickly as possible. Further, given the demanding environment in which railroad trains operate, any system must be rugged, reliable and able to operate for long periods with little or no maintenance. In addition, to be cost effective, it should not add significant cost to install and maintain the system. Since there are more than 1.5 million freight cars in North America alone, and a system of monitoring all cars in use is highly desirable, any such system need to be able to deal with a very large address a very large number of potential devices.
One approach widely adopted in North America is to use wayside defect detectors at fixed locations throughout the railroad network. Detectors measuring bearing temperature (hotbox detectors) are common, while other wayside detectors to measure wheel impacts, bearing condition (from acoustical signatures) and lateral forces are gradually being introduced. However, while one detector can monitor many freight cars as they pass, they can only provide a spot check on performance. It is quite possible that defects will only become apparent and escalate to a critical level between detectors. A system which is continuously monitoring railcar performance is needed.
Another approach to railcar performance monitoring has been to use on-board instrumentation. One such prominent system has been developed for the Federal Railroad Administration. In this and other similar systems, a number of instruments on different areas of a freight car are used to make discrete measurements before being communicated to a central hub on the freight car. While providing a superior solution to that provided by wayside monitors, wiring, complexity and costs increase the investment required to monitor the cars.